This invention relates to improved jacking mechanisms for lowering casing or other pipe into a well.
In our prior copending application Ser. No. 6/169,718 entitled "Well Casing Jack Mechanism", we have disclosed a casing jack which is adapted to be positioned in a well drilling rig and which can be utilized for lowering a string of casing into a well drilled by the rig. The jack is especially desirable for use in connection with deep wells in which the casing string may be too heavy to be suspended and lowered by the traveling block and other conventional equipment of the rig. The jack of that prior application may be positioned in the rig at essentially the location at which the rotary table is mounted during drilling, and preferably includes piston and cylinder mechanisms at different sides of the well axis for relatively vertically actuating two gripping units to progressively lower the casing.